<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style type="text/css">
        div strong {
            color: red;
            font-size: 50px;
        }
        div div p {
            color: green;
            font-size: 30px;
        }
        /* 更加精确的选择*/
        div div div span strong {
            color: blue;
            font-size: 60px;
        }
    </style>
    <title>Document</title>
</head>
<body>
    <div>
        <div>
            <div>
                <span>
                    <strong>123</strong>
                </span>
            </div>
        </div>
    </div>
    <div>
        <div>
            <p>1234</p>
        </div>
    </div>
    <div>
        <div>
            <div>
                <strong>1235</strong>
            </div>
        </div>
    </div>
</body>
</html>